1. Field of the Invention
The invention relates generally to mixing agitators useful with scraping elements and particularly to arrangements for mounting scraping elements to such agitators.
2. Description of the Prior Art
Agitator structures have long been used to mix foods, cosmetics, pharmaceuticals and many other materials in kettles or in containers of various shapes and sizes. Prior agitators have often been provided with scraping elements so that interior surfaces of the kettle or container could be continually scraped during the mixing process. In those situations wherein the materials to be mixed consist of liquids having suspended solids such as often occurs in the mixing of foods and especially foods which are being heated and/or cooked, it is necessary to gently and thoroughly mix the food materials without damaging the suspended solids. Agitators capable of mixing such materials with at least some degree of efficiency have previously been proposed. For example, Groen, Jr. in U.S. Pat. No. 3,752,057, describes an agitator having scraping elements which extend into the open end of a mixing kettle. The shaft upon which the Groen, Jr. agitator rotates extends diagonally into the kettle with the scraping elements being maintained in contact with interior surfaces of the kettle by virtue of an accurate placement of the agitator shaft relative to the kettle. Giusti, in U.S. Pat. No. 4,199,266, discloses an agitator mounted for rotation about a horizontal axis within a mixing kettle. Giusti provides scraping elements which are mounted in fixed positions on the agitator, the scraping elements of Giusti not being capable of pivotal movement by virtue of structure mounting the scraping elements to the agitator. Accordingly, the scraping elements of Giusti do not continuously "track" the interior surfaces of a kettle especially when these interior surfaces are "out of round". Brubaker, in U.S. Pat. No. 4,095,307, provides scraping elements on a mixing agitator, the scraping elements being spring biased to facilitate contact between walls of a container and the scraping elements. Pardo et al, in U.S. Pat. Nos. 4,571,091; 4,790,667; and 4,818,116 describe agitator structures having scraping elements which continuously track the interior surfaces of a kettle within which materials are being mixed, the scraping elements being resiliently biased into contact with interior surfaces of the kettle even when these interior surfaces are "out of round". The agitators of Pardo et al are particularly useful in mixing liquids having suspended solids and wherein the materials are being heated and/or cooked. The continual and substantially complete mixing and scraping action of the Pardo et al agitators facilitate suspension of solids in the mixture without damage to the solids and also act to prevent "burn-on" of food materials to walls of the kettle during mixing and/or cooking. The Pardo et al agitators exhibit extremely efficient mixing and scraping actions due in part to the ability of the scraping elements to maintain contact with interior walls of a kettle even when the kettles are not manufactured with perfectly spherical interior surfaces. The scraping elements of the Pardo et al agitators are contoured with scraping edges which conform to localized portions of interior surfaces of a kettle, the scraping elements being spring biased for pivotal movement to assure contact between the scraping edges and the surfaces of the kettle. The mounting arrangement of the invention provides all of the advantages of the prior art agitator/scraper combinations such as the Pardo et al structures while being of simple construction and of inexpensive manufacture. Further, the present scraper mounting arrangement allows the scraping elements to be readily removed from the agitator for cleaning of the scraping elements and of the agitator. The present scraper mounting arrangement can also be used to mount scraping elements to agitators of widely varying structure whether horizontally or vertically or diagonally mounted for rotation within a mixing kettle.